The credits here are impressive, the plot is intriguing and the production values impeccable, but they only add up to an average wartime thriller. In common with many blockbuster writers, Emeric Pressburger (co-scripting under the pseudonym Richard Imrie) and his colleagues were confounded by the dual task of telling a ripping yarn and finding enough to do for a big-name cast (that includes George Peppard, Sophia Loren and John Mills). As a result, the mission to replace German V-2 rocket scientists with Allied boffins is often of secondary interest to the stargazing. However, there is plenty of derring-do, even though director Michael Anderson struggles to find a workable balance between action and chat.

Allied agents infiltrate the Nazi rocket complex at Peenemunde in order to obtain their secrets and sabotage the plant. The film alternates between German developments of the V-1 missile and V-2 rocket (with a German cast speaking their own language) and discovery by British Intelligence of the weapon.